Float switch



April 4, 1939- w. R. JESSUP 2,153,421

FLOAT SWITCH Filed July 9,- 1937 Fig.5 5: 72 5 5 5 79 5 William Q.dessup Patented Apr. 4, 1939 UNITED STATES EATENT OFFICE 5 Claims.

My invention relates to improvements in float switches for tanksparticularly, though not exclusively, for oil tanks for domestic oilburners, an object of the invention being to provide a simple, durableand inexpensive float switch which is readily applicable to any ordinaryoil tank, without alteration of the tank, and which is adapted to bequickly and easily adjusted and repaired.

Another object of the invention is to supply a switch of the presentcharacter having a housing providing two compartments, one for actuatingparts and one for switch parts, each compartment being individuallyaccessible to give access to its respectively contained partsindependently of and apart from the parts contained in the othercompartment.

A further object of the invention is to supply a float switch, as above,in which one compartment of the housing communicates with the interiorof the tank and the other compartment is segregated from the first bymeans of a partition providing a bearing for a rocker member employed tomove a switch part in said second compartment in response to themovement of an actuating member in said first compartment, suchconstruction barring the transmission to said first compartment ofburning gases ignited in said second compartment.

With the foregoing and other objects in view, which will appear in thefollowing description, the invention resides in the novel combinationand arrangement of parts and in the details of construction hereinafterdescribed and claimed.

In the drawing:

Fig. 1 is a perspective view showing an embodiment of my invention infloat switches applied to an oil tank.

Fig. 2 is a vertical sectional view in detail of the switch and aportion of the tank shown in Fig. 1, said view being taken as on line2--2 of said Fig. 1.

Fig. 3 is a horizontal sectional view taken as on the line 3-3 of Fig. 2and drawn to a somewhat smaller scale than Fig. 2.

Fig. 4 is a fragmentary longitudinal sectional view of the float showingits adjustable application to the lower end of the float rod.

Fig. 5 is an elevational view of the switch case or housing with the capremoved from the lateral branch thereof, said view showing the switchparts within said branch.

In supplying oil to domestic oil burners, it is common practice toutilize oil tanks of substantially 250 gallons capacity. In purchasingoil in quantity less than 200 gallons, the price is usually greater thanthat charged for the same quality of oil in quantity equal to or inexcess of 200 gallons.

It is, therefore, desirable from an economical standpoint to purchase200 or more gallons of oil at a time, such method of purchasing beingfurther desirable since it minimizes the frequency of the failure of hisburner for lack of fuel, not to mention the extra expense to which he isput in securing special deliveries of oil and the special services ofburner service men which are often required in re-starting a burner. Thepresent invention provides a mechanism which eliminates thisinconvenience and expense by immediately informing the user when the oilin the tank reaches a level at which the tank will accommodate apredetermined replenishing charge and yet will continue to supply oil inpredetermined quantity.

For the purpose of illustrating the application of my invention, I haveshown a conventional oil tank In such as used in connection withdomestic oil burners, said tank including a body I I of sheet metalhaving end walls [2. Welded to the lowermost portion M of the body IIare brackets it: which rest on legs I6 fitted with floor flanges H. Inthe uppermost portion H) of the body I! of tank 10 are tapped fittingsl9, 2i) and 2 I, fitting l8 accommodating a filler pipe 22, fitting 2iaccommodating a vent pipe 23 and fitting 20 providing a third openinginto the tank to give access thereto or for any other desired purpose.

My improved float switch, as illustrated, comprises an upright tubularcase or housing 25 having an open upper end 25. The lower end of thecase 24 is closed and formed to provide a plug 26 which is threaded at21 to screw into a threaded fitting such as fitting 2!] in the tank ID.If desired, a sealing gasket (not shown) may be placed between theshoulder 28 on case 24 and the lip 29 of the fitting 20. To facilitatescrewing the plug 26 into fitting 20, the lower end of the case 24 isconstructed with a wrench engaging portion 3!), preferably hexagonal inform.

The case 24 has a lateral tubular branch 3! with an open outer end 32. Apartition 33 is formed at the junction between the case 24 and thebranch 3|, a compartment 34 being provided in the case proper at oneside of said partition and a compartment 35 being provided in the branch3| at the other side of the partition. This partition is formed with anelongated boss 36 issuing into the compartment 35 in said branch 3|.

The upper end of the case 24 is threaded externally as at 38. A cap 39screws upon these threads 38 and serves to close the open end 25 of saidcase, a gas tight connection between the cap 39 and the case proper,being provided by the employment of a gasket 40 between said cap and thelip 31 of the case. The outer end 32 of the branch 3| is provided withexternal threads 42 to receive a cap 43, a sealing gasket 44 beinginterposed between said cap 43 and the lip 4| of said branch 3|.

A mercury switch 45 is employed, the same being of ordinary constructionand such as is now well known in the art. This switch includes a tube orcapsule 46 of glass or other suitable rnaterial, said tube beingprovided with contacts 4'! projecting into the interior thereof. Withinthe tube is a globule of mercury 48 which is adapted to make anelectrical connection between the two contacts 41 when the tube 48 is inone inclined position (dotted lines, Fig. 5) and to break suchconnection when said tube is in an oppositely inclined position (solidlines, Fig. 5). Also within the tube 46 is an inert gas in the presenceof which sparking is effectually minimized. Flexible conductors 5|,connected with the contacts 41, connect the switch 45 in the circuit inwhich it is used.

The switch 45 is mounted for oscillation, as follows: The boss 36 on thepartition 33 has an axial bore 52 extending therethrough and throughsaid partition. This boss 36 constitutes a bearing for an arm 54 whichis in the form of a shaft, the same being bent at one end portionthereof to provide a crank 54b and being reduced and threaded at theother end portion thereof to provide a shouldered support Me. Thecylindrical shank portion 54a of the arm 54 is revolubly disposed withinthe bore 52 of the boss 35 with the crank 54b thereon within thecompartment 34 of the case 24 and the support 54c within the compartment35 of the branch 3!. A carrier plate 53 is centrally apertured toreceive the support 540 formed by the reduced end of the arm 54, saidplate 53 being clamped between the shoulder (not shown) of said supportand a clamping nut 58 threaded on said support. Riveted to thecarrier-plate 53, above the center thereof, is a clip 55 formed withbent fingers 56 which embrace the tube 46 and hold it in a fixedposition relative to said carrier-plate, as shown. Riveted also to thecarrier-plate 53, but below the center thereof, is a weight 51,cylindrical in form, the axis of said weight being disposed inparallelism with respect to the axis of the shank portion 54a of the arm54. Unimpeded, this weight 51 serves to turn the rock arm 54 in aclockwise direction, as seen in Fig. 5, and thus shift the switch tube46 from the position thereof shown in dotted lines (Fig. 5) to theposition shown in solid lines. Formed integrally with the wall of thecase or housing branch 3! is an in wardly issuing lug 3m forming a limitstop against which the weight 51 abuts, when it reaches the bottom ofits gravitating swing.

The mechanism for operating the switch 45 to close the circuittherethrough includes a float rod 63 vertically disposed and guided forvertical movement in a guide tube 64. This tube is attached to the plug26, the upper end of said tube being pressed into an axial bore 65formed in said plug. Attached to the lower end of the rod 63 is a float52 comprising an elongated hollow body of light sheet metal having anaxial sleeve 65a therein. The float rod 63 extends through said axialsleeve 66a of float 56, said float being held in place on said rodbetween spaced collars liilb secured to said red by means of set screws660. The float 63 is of such diameter as to be insertable into the tankthrough the opening in the fitting 26.

The upper portion of the float rod 63 is threaded as at ii and a metaldisc 72, centrally apertured to receive the rod, is applied to thethreaded portion of said rod between two nuts 13 and i4 which engagesaid disc at either side thereof and rigidly clamp it in place on saidrod. This disc l2 overlies the crank 54b of arm 54 and, upon the descentof the float rod 63, said disc acts to engage said crank and turn therock arm 54, against the influence of the weight 51, into positionclosing the switch 45. A stop nut 69, threaded on the float rod 53, isdisposed thereon in position to engage the upper end of the guide tube64 and arrest the descent of said float rod when the crank 54b is turnedfor enough to close the switch as. The ascent of the float rod 63 islimited by the cap 33 against which the upper end of said float rodnormally abuts. The adjustment of the disc 12 on rod E3 provides for theengagement of said disc with the crank 54b of arm 54 earlier or later inthe descent of said rod 63, such adjustment being if desired, tosupplement the adjustment of the float 66 on said rod 53. The relativeangular relation of the swi ch tube weight 5'1 and crank 5d?) of arm 5:5is such that the weight 57, unimpeded, will, by gravity, cause theswitch tube 45 to assume position as shown in solid lines in Fig. 5,wherein the switch 45 is open and, at the same time, will cause thecrank 54b of arm 54 to assume an angular position somewhat above theaxis of the shank portion 54d of the s: d arm. This relation of partsobtaining, the crank 54!) of the rock arm 54 is swung downwardly by thedisc I2, upon the descent of the rod 63, thus turning the arm 54 andshifting the tube 43. against the action of the weight 51, into aposition as shown in dotted lines in Fig. 5, wherein the switch 45 isclosed.

The disc 12 being disposed above the crank 5417, the ascent of float rod63 is unimpeded thereby. Owing to its form, the disc 12 properly engagesthe crank 54?], regardless of the angular disposition of the float rod63 in relation to the case 24.

The flexible conductors SI of switch 45 are connected to contact posts1! extending through the wall of the housing branch 3|, said posts, inturn being connected in a circuit 81. This circuit ll! may include anelectric lamp 82 and the s condary 83 of a transformer 84 whose primaryB5 is connected to any suitable source of electric current. Thetransformer 84 furnishes electrical cur ent for operating the lamp 82when the switch li: is closed, said lamp 82 being at some convenientlocality where an attendant will promptly observe the lamp when lighted.

In applying the device to any given oil tank, the principal adjustmentto be made to suit the particular tank, is the adjustment of the float66 on the float rod In making this adjustment, the float 55 is securedto float rod 63 in such position thereon that the buoyancy of the fioatin the oil will support the rod 63 and hold it with the upper endthereof abutting against the cap 39 only until enough of the oil hasbeen consumed to permit the replenishing of the supply in predeterminedquantity. When this stage of the oil in the tank has been reached thefloat 66 together with the float rod 63 should promptly begin to descendas the oil continues to be drawn from the tank. In such descent of thefloat rod, the disc 12 engages the crank 54b of rock arm 54 and turnssaid arm to close the switch 45 (dotted lines, Fig. whereby notice isgiven, through lamp 82, of the demand of the tank for the usualrefilling charge and of the limited oil supply remaining in the tank. Insome installations, it is convenient in very closely adjusting thedevice to supplement the float adjustment by adjusting the disc '52 onthe float rod 63, said disc is caused to engage the crank 54?) of arm 54earlier in the descent of the float 66, whereby the switch 45 is morepromptly closed after the tank can accommodate the predeterminedrefilling charge. By elevating the disc 12 on rod 63, the oppositeresult is obtained. Depending upon any adjustment of the disc 12 thatmay be made, the stop nut 65 is correspondingly adjusted to keep thedead weight of the float 66 and rod 53 from being applied to the rockarm 54 through the engagement of the disc 12 with the crank portion 54bof said arm. When the signal lamp 82 has been lighted by closing theswitch 45, said lamp remains lighted until oil is added to the tank. Asthe oil rises in the tank, upon the refilling thereof, the float 66 andfloat rod 63 rise with the oil until the upper end of the rod 63 reachesthe cap 39. During this short upward movement of the float rod 63, thedisc 12 frees the crank 54b of the rock arm 54, said arm being thereuponturned by the weight 5'! into position to open the switch 45 (solidlines, Fig. 5) and cut off the current to the lamp 82. As thereplenishment of the oil supply in the tank continues, the float is heldsubmerged in the oil and no further movement of the switch actuatingmechanism occurs until the level of the oil again falls below thecritical level. At such time, the float 66 and rod 63 start to descend,the continuing descent thereof causing the turning of the crank 5411,through the medium of disc 12, and the consequent closing of the switch45. When it is desired to ascertain the amount of oil within the tankbefore the critical level has been reached, the cap 39 is unscrewed andremoved from the case 24, thus permitting rod 63 to rise through theaction of the float 66. By reference to the lowermost of the visiblegraduations 61 which are suitably formed on the rod 63, the quantity ofoil within the tank can be quite accurately determined. Normally, thecaps 39 and 43 are kept in place to confine the gases from the oil inthe tank to said tank and to the case 24.

The length of the boss 35 and the clearance between the shank 54a of arm54 and the wall of the bore 52 in said boss are such as to remove anypossibility of an explosion of gases in the compartment 3 of case 24 andthe tank [0, as the result of an explosion in the switch compartment 35of branch 3!. Ample clearance in its bearing for the free rockingmovement of the arm 54 is necessary, yet the length of the bearing inrelation to the clearance is such that burning gases, fired within theswitch compartment 35, cannot make their way about the shank 54a, of arm54 to the compartment 34 of the case 24. In practice, I have found thata bore in the boss 36 of one and one-eighth inches in length and aclearance of five one thousandths of an inch between the shank 54a andthe wall of such bore will provide for the free rocking movement of thearm 54 and, too, will effectively confine burning gases to the switchcompartment 35 of the.

case 24, whereby dependability of operation, without danger of explosionin the oil tank, is assured.

Changes in the specific form of my invention, as herein disclosed, maybe made within the scope of what is claimed without departing from thespirit of my invention.

Having described my invention, what I claim as newand desire to protectby Letters Patent is:

1. A unitary device of the character described comprising an uprightcase formed with a horizontal branch, the case having an opening at itsupper end and a removable cap normally closing said opening, said branchhaving an opening at its outer end and a removable cap normally closingthe opening therein, a plug at the lower end of the case for attachmentto a fitting in an opening in the top of a tank, a float rod, said plughaving a bore therein slidably receiving said rod for vertical movement,a float mounted on the lower portion of said rod and adapted with said 1portion of said rod to be passed through said tank fitting andpositioned within the tank, arm rockably mounted within the device, theouter end of said arm being disposed within said branch and the innerend thereof within the case, an electric switch within said branch, saidswitch having a part movable with said arm, means within said branchacting on said arm to move the arm in one direction and throw off theswitch, an actuating member mounted on the upper portion of the floatrod and adapted, upon the descent of said rod, to engage the inner endof said arm from above and move the arm to throw on the switch, theopening in the case initially admitting said actuating member to thecase, the opening in the branch. initially admitting said switch andcompanion parts to said branch, the removal of the cap from the casenormally affording access to said actuating mem" her and to the interiorof the case and its contained parts independently of and apart from thebranch and the parts contained therein, the removal of the cap from theouter end of said branch normally affording access to the switch andcompanion parts independently of and apart from the case proper and theparts contained therein.

2. A unitary device of the character described comprising an uprightcase having a plug at its lower end for attachment to a fitting for anopening in the top of a tank, a float rod, said plug having a boretherein slidably receiving said rod for vertical movement, a floatmounted on the lower portion of said rod and adapted with said portionof said rod to be positioned within said tank, said case having ahorizontal branch, an electric switch within said branch, an armrockably mounted within the device, the outer end of said arm beingdisposed within said branch and the inner end thereof within the case,said switch having a part movable with said arm, means acting on theouter end of said arm to move the arm in one direction and throw off theswitch, an actuating member adiustably mounted on the upper portion ofthe float rod and adapted, upon the descent of the float rod, to engagethe inner end of said arm from above and move the arm to throw on theswitch, a sealing cap at the top of said case, said cap being removableto lend access to the interior of the case and its contained parts, anda second sealing cap applied to the outer end of said branch andremovable therefrom to lend access to its contained switch and companionparts independently of and apart from the case proper and the partscontained therein.

3. A unitary device of the character described comprising an uprightcase having a plug at its lower end for attachment to a fitting for anopening in the top of a tank, a float rod, said plug having a boretherein slidably receiving said rod for vertical movement, a floatmounted on the lower portion of said rod and adapted with said portionof said rod to be positioned within said tank, said case having ahorizontal branch, a partition segregating the interior of the case fromthe interior of said branch, said partition having an elongated bearingboss thereon pro- J'ecting into said branch and formed with an axialcylindrical bore extending therethrough and through said partition, anarm having a cylindrical shank portion and a crank at one end thereof, amercury switch within said branch, said shank portion of said arm beingrockably received in said bore, the crank on said arm being disposedwithin the case proper and the end of said shank opposite said crankbeing disposed with said branch, a carrier member mounted on said end ofsaid shank, said switch being mounted on said carrier member, a weightalso mounted on said member and acting on said arm to turn the same inone direction to throw off the switch, an actuating member mounted onthe upper portion of the float rod and adapted, upon the descent of saidrod, to act upon said crank and turn the arm in the other direction tothrow on the switch, the clearance between the shank of said arm and thewall of the bore in said bearing boss being limited in relation to thelength of said bore to prevent burning gases, ignited by the switch insaid branch from reaching the gases in the case through said partition.

4. A unitary device of the character described comprising an uprightcase having a plug at its lower end for attachment to a fitting for anopening in the top of a tank, a float rod, said plug having a boretherein slidably receiving said rod for vertical movement, a floatmounted on the lower portion of said rod and adapted with said portionof said rod to be positioned within said tank, said case having ahorizontal branch, a partition segregating the interior of the case fromthe interior of said branch, said partition having an enlongated bearingboss thereon, formed with a bore extending therethrough and through saidpartition, an arm movably received in said bore, an electric switchwithin said branch, the outer end of said arm being disposed within thecase proper and the inner end thereof within said branch, said switchhaving a part movable with said inner end of said arm, means acting onsaid arm to move the same in one direction to throw ofi the switch,

actuating member mounted on the upper portion of the float rod andadapted, upon the descent of said rod, to act upon and move said arm inthe other direction to throw on the switch, the clearance between saidarm and the wall of the bore in said bearing boss being limited inrelation to the length of said bore to prevent burning gases, ignited bythe switch in said branch, from reaching the gases in the case throughsaid partition.

5. A unitary device of the character described comprising an uprightcase for intercommunicating attachment to a tank, a float rod having oneend portion thereof disposed within the case, a float mounted on theother end portion of said rod and adapted therewith to be positionedwithsaid tank, said, case having a branch, a partition segregating theinterior of the case proper from the interior of said branch, an armextending through the partition, the outer end of said arm beingdisposed within the case and the inner end thereof within said branch, abearing on said partition movably supporting said arm, an electricswitch within said branch, said switch having a part movable with saidinner end of said arm, means acting on said arm to move the same in onedirection to throw oif the switch, an actuating member mounted on saidportion of the float rod within the case and adapted, upon the descentof said rod, to act upon and move said arm in the other direction tothrow on the switch, said bearing for said arm. being formed to preventburning gases, ignited by the switch in said branch, from reaching thegases in the case through said partition.

WILLIAM R. JESSUP.

